The nasal gland of the gull can secrete a solution of sodium chloride about 5 to 6 times more concentrated than that found in blood plasma. The gland can also concentrate iodide to several times the plasma concentration, but chloride seems to be preferred in the secretory process. These experiments were undertaken in the hope that a particularly high iodide clearance could form the basis of a method for determining the blood flow to the gland. The results made this approach to blood flow measurements unfeasible.